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Front end vibration?


pbtexan

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Taking my 89 Reatta w 17k miles to the shop today for brake flush (DOT 3 Synthetic) and poss Plugs/wires/others as needed (running a little rough, intermittently)

Problem developed on the front end a few weeks ago:

   At light acceleration, in the 60-70 mph range, front end begins vibrating,  starts with small oscillation then gets very pronounced within a few seconds.

   I can slow down to 55, til it stops, then accelerate a little more vigorously and it moves through 60-70 without happening again.

   Doesn't happen all the time, just sometimes getting up to speed on expressway.

   Had it happen today on back road at 37-40 mph.   Pushed "through" it by accelerating more and it stopped.

Previous tires were Michelin 2009 with 95% tread left, but a friend convinced me the belts were going, so I put a new set of Continentals on (4720 date codes) this past weekend.   No issues yesterday morning on the way to work, but happened on the way home yesterday at 60 mph.

Would say that vibration starts at severity 1 then quickly moves to 5+  (10 is where parts start to fall off)

 

Any idea what is causing this on a low mileage car?  Transmission?, bearing, tie rods, heck I'm clueless !  Dont want the dealership to run over me on this first visit LOL

 

thanks 

 

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Safety first! Make sure the tires are good and aren't dry rotted. The problem sounds to me like an ignition problem, breaking down under acceleration and lower speeds. The next time it does it just lightly press on the brake pedal and see if the vibration goes away. Doing that will cause the torque converter to unlock and take some of the load off the engine. If the vibration goes away the engine missing is likely causing the vibration.

 

Oh, BTW, Do you feel the vibration mostly in the steering wheel or the whole car?

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Whole car !  Front end and Dashboard starts bouncing !

I'll try to replicate it this afternoon on the way home  so I can try the brake tap.

Its still happening w the brand new continentals I gave them a quick visual when I got home from the tireshop Saturday, but did not study them since they are less than a year old.

 

Thanks for the tips

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I was afraid its a major steering link or trans failure, but those would be "constant" vs intermittent, right?

 

Cannot get it to replicate every time I "pass through" that speed range, so I was betting it was not the tires, (but spent the money on new ones anyway)

 

thanks 

 

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24 minutes ago, pbtexan said:

I was afraid its a major steering link or trans failure, but those would be "constant" vs intermittent, right?

I agree. When you do the test with the brake to unlock the converter, do it when the you are accelerating up a long incline so the transmission is in 4th gear and the converter is locked and you feel it vibrating. If you lay your food on the brake pedal the converter should unlock. If that causes the vibration to go away you can be pretty certain the problem is with the engine missing. Most likely bad spark wires and/or spark plugs.

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Did the tire place give the front end a once over when they installed new tires? Were they made aware of the intermittent vibration issue?

 

Engine misfire could cause this issue as Ronnie mentioned but would have to be pretty severe. If at the shop for possible plugs and wires, check the coil pack and ICM closely.

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I DID mention it to the tire shop, but it was a Saturday morning appt at Discount tire, and they did not give me any feedback on issues.... not sure they tried very hard, since mounting and balancing is about the max of their work.

 

I will make sure the Dealership gives the front end a good going over.  And ALSO check out the plugs, wires, Coil pack and ICM.

 

I think I bought an "experienced take off" coil pack from one of the ROJs to keep in my trunk for emergency, but imagine they would probably guide me to installing their new product.  

 

If it comes to coil pack and ICM... what should I be prepared to pay for parts?

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Found some prices on autozone and rock auto.  looks like 60-70 for the coil pack and 110 to 125 for  ICM  from standard or dephi or duralast..   acdelco about 50% more on each 

 

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3 hours ago, pbtexan said:

I think I bought an "experienced take off" coil pack from one of the ROJs to keep in my trunk for emergency,

Bought from one of the ROJs?

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Don't think it's a bent wheel, the tire store did not say anything about that, and it is not a reproduce-able event every time.   

The engine has recently had a little roughness at idle and during slow driving.

Another friend suggested that if the ignition system is failing, and it's dropping a cylinder or two, it could certainly create enough vibration to give that feeling., That, coupled with the other comments above, leads me to think it may be ignition/spark/ etc related.

 

We'll see what the dealership comes up with,  I think it would be "less of two evils" if it is the ignition vs front end, just because I was planning to do a plugs and wires replacment anyway as part of a tune up.  Hoping to avoide the coil and ICM, but if that's the cure then thats the price of 32 year old electronics and wires and plugs !  

Fingers (and credit card) crossed !

😉

 

 

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Yeah, Ronnie,  not sure if it was Dave or someone else.  When I first got the car last year I asked the group what I should acquire to prevent a roadside breakdown and hard to find parts.

One thing was the coil pack and the hard to find was the CRT,  so I bought a reworked CRT from someone (it might have been Dave89-   Dave if it wasn't you, my apologies)  and the same person had either a new or recently "take off for upgrades part"  coil pack at the same time.

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35 minutes ago, pbtexan said:

Yeah, Ronnie,  not sure if it was Dave or someone else.  When I first got the car last year I asked the group what I should acquire to prevent a roadside breakdown and hard to find parts.

OK I understand. I though you might have bought parts from someone representing this website but you meant one of our members. Glad someone was able to supply the parts you  needed.

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  • 2 weeks later...

OK, update on the service work!.

So, after a new set of Continentals, balanced the moderate vibration was still occuring at 65 to 75 mph

Not repeatable on demand, but would happen once in every leg of the commute.

 

Took "RR" to the buick dealer for Brake fluid flush (2 quarts of preston dot 3 synthetic) and a synthetic oil change and front end alignment.  Plus "quality check" on the coolant and trans fluids.

Service Writer A said he was able to get the vibration to repeat, but not when the tech was with him. He went out on vacation for a week so I picked the car up Wed pm.  No problem on the way home, but the Vibration reoccurred yesterday on the way home and today on the commute to work.  

TOday's Vibration issue lasted for several miles (instead of a 15 second episod) and I was able to get it to repeat several times.  DEFINATELY happens under acceleration or "load" - stops completely when I let off the gas and coast a little (still at cruising speeds, with light throttle pressure, but not trying to accelerate). 

 

Re occured several times with light to moderate acceleration attempts.   Finally slowed down to 60, where it stopped, then applied moderate acceleration and moved up to 75 without incident. 

 

There is some tach motion during this time, but no wild swings (up or down 25 rpm at 1750 to 2100 rpm range) 

 

Vibration starts very faint, then escalates up as more throttle is given to the point of whole car vibrating uncomfortably.

 

I don't know if the dealership doesn't know HOW to diagnosis the electrical system or not.

 

I don't think it's tires or front end, and the fuel system has had some cleaner through it.  I've run various cleaners (techron and one other) through the tank, and the Service Writer B told me to run some RXP through it.  Could not find that last night on the way home, so tried a can of Seafoam (16 oz to 8 gal 89 Octane gas) last night, and it definitely did not help it today

 

So, I'm think electrical (plugs, wires, coil and ICM or perhaps something else?

Could it be a vacuum gremlin?

 

And I thought the 3.8 engine would be a snap to diagnose,  LOL

 

Any thoughts on next steps?   If the dealership can't test the plugs, wires, coils and ICM do I just bite the bullet and change them all?

 

thanks !!

 

 

 

Edited by pbtexan
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Twere me, I'd jack it up and test all of the motor and transmission mounts. Have seen a tranny mount act like that before. Also check the torque strut on top for gone rubber. ANYTHING that has rubber that is worn & can result in metal to metal contact, even a bad sway bar mount, can cause vibration.

 

ps I used to live in Azle and work at (then) GD.

Edited by Padgett
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Padgett

Thanks for the tip !  I will have them run over every rubber bushing in front !   I had no idea they could cause intermittant failures like that, but it makes sense that "under acceleration load" they could behave differently !!

Appreciate it !

General Dynamics was home to a lot of engineers and high level machine personnel in its day,  I think it still survives in some form in the DFW area!

My Father in law worked there as well after WW2 (Corsair and Mustang mechanic) and retired in the 80s

Small world !

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On 8/13/2021 at 1:41 PM, pbtexan said:

TOday's Vibration issue lasted for several miles (instead of a 15 second episod) and I was able to get it to repeat several times.  DEFINATELY happens under acceleration or "load" - stops completely when I let off the gas and coast a little (still at cruising speeds, with light throttle pressure, but not trying to accelerate). 

 

Re occured several times with light to moderate acceleration attempts.   Finally slowed down to 60, where it stopped, then applied moderate acceleration and moved up to 75 without incident. 

 

There is some tach motion during this time, but no wild swings (up or down 25 rpm at 1750 to 2100 rpm range) 

 

Vibration starts very faint, then escalates up as more throttle is given to the point of whole car vibrating uncomfortably.

 

I don't know if the dealership doesn't know HOW to diagnosis the electrical system or not.

 

I don't think it's tires or front end, and the fuel system has had some cleaner through it.  I've run various cleaners (techron and one other) through the tank, and the Service Writer B told me to run some RXP through it.  Could not find that last night on the way home, so tried a can of Seafoam (16 oz to 8 gal 89 Octane gas) last night, and it definitely did not help it today

 

So, I'm think electrical (plugs, wires, coil and ICM or perhaps something else?

Could it be a vacuum gremlin?

 

And I thought the 3.8 engine would be a snap to diagnose,  LOL

 

Any thoughts on next steps?   If the dealership can't test the plugs, wires, coils and ICM do I just bite the bullet and change them all?

You are describing the classic signs of a secondary ignition system problem. Spark plugs or wires is my first thought when I hear this. That's what
I would start with and move on to the more expensive parts if that doesn't correct the problem.

 

Diagnostics won't help with secondary ignition problems or fuel pressure. Fuel pressure is easy to check and should be checked if you haven't already done so.

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Ron Walker

No, I have not run the codes... meant to this weekend but several other projects (honey-do's)!


Ronnie

Thanks,  if you think I might get away with plugs and wires, I'll go that route first!

 

If I have to go further, do I do coil pak first or ICM first, or both at the same time?

 

I'll have them check the fuel pressure while it's there

 

 

thanks

Edited by pbtexan
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2 hours ago, pbtexan said:

Ronnie

Thanks,  if you think I might get away with plugs and wires, I'll go that route first!

 

If I have to go further, do I do coil pak first or ICM first, or both at the same time?

If it were mine I would try plugs and wires first. Then ICM and then coil pack to avoid buying any more parts than necessary since there is no guarantee that any of them with fix the problem. Since you are scheduling time and paying dealership prices you should go with their advice. Their advice is what you are paying the big bucks for.

 

My advice from my keyboard is based on past experience and applying it to the symptoms you describe in your posts. Nothing beats laying hands on it to do some testing to come up with a diagnosis and that is what they should do when you take it to them.

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